Japanese Unexamined Patent Publication No. 6-293501 discloses a process for decomposing chlorofluorocarbons, involving heating magnetite by application of microwaves in an applicator, and then contacting the heated magnetite with chlorofluorocarbon gas. Also, Japanese Unexamined Patent Publication No. 7-24255 discloses a process for decomposing chlorofluorocarbons involving microwave irradiation of a mixture comprising a carbonaceous material and an alkaline earth metal oxide or salt for heat generation, and then contacting of the heated mixture with chlorofluorocarbon gas.
Since the chlorofluorocarbon-decomposing processes in the aforementioned publications all employ microwaves, their drawbacks have been the requirement of costly microwave-generating apparatuses and reactors limited to heat-resistant materials with good permeability to microwaves. Ceramics are materials with good permeability to microwaves, but these tend to react with fluorine and thus deteriorate in quality. Consequently, industrially economical and stable decomposition of chlorofluorocarbons is a problem for which a solution has been sought.
One technique for decomposing chlorofluorocarbons without using microwaves has been proposed in Japanese Unexamined Patent Publication No. 8-187302 by the present applicant, which is a chlorofluorocarbon decomposition process wherein chlorofluorocarbon gas is contacted and reacted with a substance containing a carbonaceous material and an alkaline earth metal compound heated in a non-oxidizing atmosphere. The process of this prior application has the advantage of allowing decomposition of chlorofluorocarbons using a normal heating furnace with an electrical heater, and as stated in the related specification, chlorofluorocarbons such as R-113 may be efficiently decomposed.
Nevertheless, subsequent research has revealed that many kinds of fluorocarbons are not decomposed by the process of this prior application, and the decomposition rate is not necessarily satisfactory for fluorocarbons with no chlorine groups, such as perfluorocarbons and hydrofluorocarbons, which are not mentioned in the specification of the prior application.